At buildings and at many other occasions it is desirable and necessary to drain off rainwater, in order to prevent damages and settlings by moisture. A problem heretofore unsolved in conventional drain pipes is, that the pipes after some time of use almost always clog with mud and must be dug out for exchange or cleaning, which involves large expenses. The problem arises in the earthenware pipes known since long ago as well as in the plastic pipes, which are provided with holes or slits and applied to an increasing extent though the plastic pipes are of such doubtful reliability, that they are banned by some local authorities.
The present invention, therefore, has the object to produce a drain pipe, which ensures efficient draining for a very long time without getting clogged by mud, and which at the same time is easy to manufacture and mount.
For achieving this object, the pipe according to the invention comprises an outer pipe, which is slitted on its lower surface. From the edges on both sides of the slit longitudinal walls are fixed. Holes or openings provided at the upper edges of the walls establish connection between the space located between the walls and the two spaces between the walls and the pipe proper. Drain water arising through the slit in the pipe between the inner walls can through this structure flow over into the two lateral channels of the drain pipe. The likelihood of clogging by mud is hereby reduced substantially, because, firstly, the water always must move upward before entering into the drain pipe. Since the mud suspended in the water is somewhat heavier than the water, the water is cleaned while arising between the walls. Secondly, the water cleaning effect is amplified by the very large drain surface, which the drain pipe provides in the form of the intermediate space between the walls, and which results in a low speed of water inflow into the drain pipe.
When the water has entered into the two drain channels on both sides of the partition walls, the drain water flows at a good speed, due to the relatively moderate flow cross-section. Said good speed ensures that mud possibly following along in these channels rapidly is transported away. This effect is improved additionally at a further development of the invention subject matter, according to which the holes or openings from the riser space for the drain water between the partition walls and into the two drain-off channels are located at different heights, so that at moderate water supply all this water is removed through the drain-off channel on one side. When this level has been exceeded, also the other channel is taken into use. Due to the generally moderate amounts of drain water, almost always only the drain-off channel, in which the openings are located at a low level, will be utilized. When this channel, for example due to unfavourable external conditions, gradually is clogged by mud, the other channel remains to be used, and the life of the drain pipe, thus, is extended substantially. In order to facilitate the manufacture of the invention subject matter, the two partition walls drawn up from the slit at the bottom of the pipe preferably are interconnected at their upper edges and/or are connected to the inner wall of the pipe with an inclined roof extending inward to each other, so that in these parts of the walls holes can be drilled or openings can be milled easily by a drill or milling cutter respectively inserted through the slit. It is hereby possible to manufacture the drain pipe by extrusion and subsequent milling operation, and the pipe, in spite of its qualified function, is not more complicated to manufacture than other known plastic drain pipes. Due to the connection of the partition walls with the inside of the pipe, besides, the resistance of the pipe in the normally vertical strain direction is increased.
In order to prevent the drain pipe from being compressed at the lower surface by the soil pressure, preferably supports for the pipe are provided, which supports, like claws embrace the pipe and maintain it in the position with the slit located downwardly, and which supports finally engage with the slit by a small plug or boss so that the slit cannot be pressed together.
In order to prevent water transport in the longitudinal direction of the pipe in the riser space for the water between the partition walls, additional walls in the form of plugs or the like are inserted equally spaced into this space. These walls can be provided, for example, at every pipe joint, if the pipe is not manufactured endless. In endless pipes it may be sufficient to provide plugs which are assembled with the aforesaid supports for the pipe.
One objection apparently obvious to be raised against the invention subject matter as to its function is, that the water would not flow into the two drain-off channels due to the rising height required for the drain water before it flows over into the drain off channels, and that the drain pipe, moreover, has no drain holes on the upper surface and, thus, would have a drain effect worse than that of conventional structures.
This argument though logical is wrong. It is not necessary for a drain pipe, as a matter of fact, to itself have the same level as the intended drain level. The conventional structures, however, prove that the designer of drain pipes heretofore has not succeeded to disengage from this wrong idea. The drain level of the invention subject matter, thus, is determined by the lower edge of the openings in the respective partition walls while the drain-off level is located below this level. It is, consequently, necessary to place the drain pipe according to the invention at a slightly greater depth than the conventional drain pipes. This greater depth, however, is smaller than the diameter of the pipe, and the insignificant increase in costs caused by the slightly greater laying depth of the drain pipe is more than compensated for by its higher efficiency and above all by its higher reliability compared with known structures.
The partition walls drawn high up in the pipe yield a further advantage of the invention subject matter over the prior art. It is thereby possible, namely, to drain off also rainwater from gutters and down pipes into drain-off channels of the drain pipe. This double utilization of the drain pipe brings about a more efficient flushing of the pipe, thereby additionally reducing the risk of clogging. At the same time the costs of a drain-off piping for the down pipe water can be saved. Besides, in this way an immediate indication is obtained when a drain pipe is clogged by mud, because then the associated down pipe will overflow. In many cases it also will be possible via the down pipe to clean one of the drain-off channels of the drain pipe so that its function can be restored. The dimensions of the drain pipe, of course, must be adapted to the calculated amount of drained-off water together with the water amount from down pipes, but the total cost for the pipe yet is lower than for two pipes having the same total capacity.